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B. H. PETER.

RAILWAY SIGNALING SYSTEM. APPLICATION FILED NOV-20. I912.

Patented Nov. 18, 1919.

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BERNJD HARTLEY PETER, OF WESTMINSTER, ENGLAND, ASSIGNDR, ,MESNE ASSIGNMENTS, TO THE UNION SWITCH & SIGNAI: COMPANY, 035 SWISSVALE, PENNSYLVANIA, A CORPDRATION OF PENNSYLVANIA;

RAILWAY SIGNALING SYSTEM.

Specification of letters Patent.

Patente new. is,

Application filed November W, 1912. serial No. 732,478.

To all whom it may concern:

Be it known that I, BERNARD HARTLEY PETER, subject of the King of Great Britain, residing at 58 Victoria street, Westminster, England, have invented new and useful Improvements in Railway Signaling Systems, of which the following is a specification.

This invention relates to railway signal ing systems ofthe kind in which an electric current for signaling purposes is supplied to circuits constituted by the track rails from any suitable source, such as a primary battery, transformer, or other source of power. In systems of the above kind the track rails are usually divided into block sections, the rails of which are ar ranged to be short-circuited as regards the signaling current supplied thereto when the section is occupied by a train, the actuation of one or-more signaling devices being arranged to be eflectedin any desired manner by this means so as to indicate the presence ofa train in the block section. Usually the signaling devices are controlled by relays which are connected across the track rails of the block sections.

According to the present invention the action of the relay is modified as regards the operation of the indicatingdevices when a train enters or leaves the block section, by the employment of one or more regulating resistances having a positive or negative temperature coeflicient which are interposed in the signaling circuit as will he hereinafter described.

In carrying the invention into practice the regulating resistance having a positive temperature co-eficient preferably comprises a.

resistance wire of iron or other suitable metal having a high positive temperature coefficient inclosed in a container which is either exhausted of air or filled with an inert gas such as hydrogen or nitrogen, the composition and density of the gas being chosen with reference to its heat conducting characteristics, so that the regulating resistance can be arranged to be heated to or cooled from a predetermined temperature within a predetermined interval of time. A similar arrangement may be adopted in connection with a resistance having a negative temperature coefficient such for instance as a carbon lamp filament.

The container may also if desired be provided with a reflector formed, for example,

by silvering the internal surface of the con- 'of heat under given current conditions to be adjusted to suit any required conditions.

The regulating resistance having a positive temperature coefficient may be arranged to be connected in series or parallel with the signaling relay usually employed for effecting the control of the signal indicating devices.

In cases in which the regulating resistance having a positive temperature coefficient is connected in series with the signaling relay, as above mentioned, its action is as follows:

Assuming that the block section corresponding to the signaling relay is occupied by a train or vehicle the difference of potential between the track rails of the block section in question is considerably reduced below its normal value, so that the current traversing the signaling relay and regulating resistance is correspondingly low, and the latter is therefore cool and of relatively good conductivity. As soon as the Vehicle or train leaves the block section the difference of potential between the track rails thereof is at once restored to its normal value and owing to the increased electro motive force acting upon the comparatively cool regulating resistance the current traversing the signaling relay is immediately increased to a value greater than its normal value, being afterward reduced to the latter as the temperature of the regulating resistance increases. The removal of the vehicle or train from the block section thus causes an abnormally high current to traverse the signaling relay for a short interval of time and insures prompt action of the latter to operate its signaling device.

As is well known to those skilled in the Mill art, the current required to cause the actuation of an electromagnetic relay of the usual type is considerably greater than that v required to maintain it in its operative position, or, in other words, the electro-motive force required to be impressed upon the terminals of the relay to insure its actuation is considerably higher than the value to which this electro-motive force can be reduced before the relay moves to its other or inoperative position. A regulating resistance connected in the manner above described is thus of great advantage in rendering the action of the relay positive and reliable when the signaling voltage across- .considerabletemperature the sudden decrease of this difference of potential due to the entrance of a vehicle or train into. the block section causes a correspondingly large reduction in the current traversing the relay and regulating resistance until the latter has had time to cool so that the short-circuiting action of the vehicle or train is assisted by the action of the regulating resistance as regards causing a decrease in the current traversing the signaling relay.

A regulating resistance of the above type may also with advantage be connected in parallel with the relay, particularly in cases in which the relays of two adjacent block sections are arranged to cooperate-in the control of a. locking device for the sig'i'i'itling apparatus.

Under these conditions it is extremely desirable that the energization of the relay of the section which the train is leaving should not take place before denergization of the relay of the section which the train is entering has occurred, or, in other words, that the regulating resistance should operate in sucha manner as to delay the energization of the first relay and accelerate the deenergization of the second relay. The action of a regulating resistance connected in the manner above mentioned is accordingly as follows:

Assuming that the train is about to leave one of the block sections, the regulating resistance corresponding to that section will evidently be comparatively cool and when the train actually leaves the section the sudden increase in the difference of potential between the track rails thereof will cause a sudden increase in the current traversing the tions in thel block section is thus to some extent delayed, so that the signaling relay of the block section which the vehicle or train is entering is enabled to respond to the sudden decrease in the difference of potential between the track rails of thissection before the relay of the other block section has operated; an interval of time between the energization and consequent movement of the second relay to a closed position and the movement of the first relay to an opened position is thus insured.

, The regulating resistance connected in parallel to the relay as above described may if desired be replaced by a regulating resistance having a negative temperature coefficient connected in series with the relay with the same result, the response of the relay provided with this form of regulating resistance being evidently retarded since the regulating resistance im edes the passage of current through the re ay until the resistance increases in temperature.

In a similar manner a regulating resistance having a positive temperature coefficient connected in series with the relay may be replaced by a regulating resistance having a negative temperature coefiicient connected in parallel with the relay, the functions of the two kinds of resistances as thus connected being the same as regards their effect on the action of the relay.

In the accompanying drawing, Figure 1 is a diagrammatic view showing the essential elements of a track circuit having a variable resistance applied thereto in accordance with one form of my invention. Fig. 2 is a dia grammatic view showing portions of two adjoining track circuits, and'va'riable resistances associated with said circuits in one manner embodying my invention. Fig. 3 is a view similar to Fig. 2 but showing another arrangement of variable resistances also embodying ncy invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the track rails of a single block section of the system are indicated at 1, the battery or other suitable source of signalin current therefor at 2, and a relay at 3 a apted to be operated in accordance with the electromotive force im pressed on the track rails 1.

The relay 3 comprises an actuating windnaansee ing connected across the track rails l, a

movable member '2 adapted to be set into the position shown in Fig. 1 when the Wind ing 6 is energized, and relay contacts 8 connected in a circuit 9. The circuit 9 may be the controlling circuit for a signal or maybe arranged to elifect the actuation of any 3, the response ot'the relay 3 to alterations.

in the circuit conditions of the block section being accelerated or retarded accordingly. y

In Fig. 2, two adjacent block sections are indicated, the track rails 1, 11. of which are insulated from one another by the usual insulating joints indicated at 12. Two relays 3, 4 corresponding to the block sectionsl and ll are provided with energizing wind ings 6, 12 respectively, the movable members 7, 13 of. the relays 3, 4: beingadapted to control a common circuit 9 Y The circuits of the energizing windings of the relays 3, 4:

are provided with regulating resistances 10, I l respectively, either or both of which have a positive or negative temperature coelficient.

Fig, 3 illustrates a modification in which the regulating resistance 10 for relay 3 is connected in parallel with the actuating winding 6 of the relay instead of in series therewith as in the preceding figures.

llt will be understood that in all the above arrangements a regulating resistance having a positive temperature coeiiicient connected in parallel with the energizing winding of the relay is the equivalent of a regulatlng resistance having a negative temperature coeilicient connected in series with the energizing winding ofthe relay and vice versa.

The invention is evidently not limited to the precise construction and arrangement of till the regulating resistance above described, which may be modified to suit.,difi"erent conditions of'operation, and may moreover be applied to" track signalin of any preferred type without exceeding t e scope of the invention.

What ll'claim is-- 1. ln combination with a track section of a railway, a source of signaling current connected with the rails thereof, a relay also connected with said rails, and a conductor interposed between said relay and one of a positive or negative temperature the rails and having the inherent property of sluggishly increasing in resistance upon increase of current flowing therethrough, whereby when a train leaves the section the current in the relayis temporarily comparatively high and is reduced after the relay has closed.

2. A, railway signaling system comprising a pair of adjacent track sections, a signaling circuit including a relay for each. section and each circuit including the rails of the corresponding section, ptraffic governing means controlled jointly by said two relays, and means associated solely with one of said signaling circuits for retarding the response of the corresponding relay to a change in the circuit conditions within the corresponding track section.

3. In combination withthe track rails of a railway, a source of signaling current and a relay connected therewith, and a' conductor connected across the terminals of said relay and having the inherent property of slugcurrent flowing therethroug 4:: ln a railway signaling system the com;- bination of a pair of adjacent block sections, a signaling circuit connected to each section, a relay connected to each circuit, means for retarding the response of one of said relays to a change in the circuit conditions within thecorresponding block section, and means for accelerating the response of the other relay to a similarchange- 5. In a railway signaling'system, the combination of a pair of adjacent block sections, a signaling system connected to each section, a separate relay located in-each circuit, and a conductor having a positive temperature coeflicient located in' one circuit in parallel with the relay and a similar conductor 10- .gishly increasing in resistance upon increase 0 cated in the other circuit'in series with the a separate relay located in each circuit, traffic governing meanscontrolled jointly by said two relays,-and,a conductor electrically connected to each circuit and having the property of varying in electrical conductivity in response to variations in the current traversing it. i In testimony whereot l[ have signed my name to this specification in the presence of two subscribing witnesses.

' Eli-NARD HARTLEY PETER. Witnesses:

H. A. Corn, v A. A. BENIN,

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